The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described herein are not admitted to be prior art by inclusion in this section.
In current Virtual Private Network (VPN) deployments, such as described in Request for Comments (RFC) 4364 and RFC 2547 of the Internet Engineering Task Force (IETF), one model of connecting Autonomous Systems (ASes) is referred to as Inter-AS Option B. According to this model, Border Gateway Protocol (BGP) is used to exchange VPN route information, such as VPN labels and prefixes, between Autonomous System Border Routers (ASBRs). In a typical implementation, provider edge (PE) routers assign Multiprotocol Label Switching (MPLS) labels for routes to customer VPN sites and distribute the labeled VPN routes using internal BGP (IBGP) to the ASBR. The ASBR then uses external BGP (EBGP) to implement next-hop self by replacing the labels of the VPN routes with a locally allocated label and distribute the newly labeled VPN routes to ASBRs in other ASes. During this process, the ASBRs do not maintain correlations between VPN routes and the VPN sites that these routes service.